查找集合模型的idAttribute

Question

在Collection的上下文中，我想基於包含模型數據的某個對象來檢索模型實例，但我不想對idAttribute進行硬編碼。

當你已經擁有一個模型實例時，Backbone會讓事情變得簡單，你可以只訪問它的.id屬性並對它進行排序，但我似乎無法找到另一種方法，而不是創建一個模型實例只是為了獲得它的idAttribute 。

例如：

var Cat = Backbone.Model.extend({
  defaults: {
    name: '',
    age: null
  },

  idAttribute: 'name'
});

var PushCollection = Backbone.Collection.extend({
  initialize: function () {
    coll = this;
    somePushConnection.on('deleted', function (deleted) {
      _.each(deleted, function (obj) {
        // obj being something like: {name: 'mittens', age: 302}
        var model = coll.get(obj[coll.model.idAttribute]); // Can't do this!
        if (model) { model.destroy(); }
      });
    });
  }
});

var Cats = PushCollection.extend({
  model: Cat
});

Answer 1

您應該能夠通過模型的原型訪問它：

Model.prototype.idAttribute

或者在您的示例代碼中

var model = coll.get(obj[coll.model.prototype.idAttribute]);

Answer 2

也許我誤解了這個問題，但你不能使用Collection.where()方法嗎？

從Backbone文檔：

其中 collection.where(attributes)

返回集合中與傳遞的屬性匹配的所有模型的數組。 適用於過濾器的簡單情況。

 var friends = new Backbone.Collection([ {name: "Athos", job: "Musketeer"}, {name: "Porthos", job: "Musketeer"}, {name: "Aramis", job: "Musketeer"}, {name: "d'Artagnan", job: "Guard"}, ]); var musketeers = friends.where({job: "Musketeer"}); alert(musketeers.length); 

所以，在你的示例代碼中：

var PushCollection = Backbone.Collection.extend({
  initialize: function () {
    coll = this;
    somePushConnection.on('deleted', function (deleted) {
      _.each(deleted, function (obj) {
        // obj being something like: {name: 'mittens', age: 302}
        var model = coll.where(obj);
        if (model) { model.destroy(); }
      });
    });
  }
});